Technical solutions are known in which safety and starting valves with rupturable diaphragms are used (U.S. Pat. No. 3,704,807, NPC 220-89, published 1972 or GB patent application No. 1138885, NPC F2V, published 1969). In these technical solutions the diaphragm breaks under the effect of pressure of the medium. These constructions do not provide the possibility of ensuring a constant flow section for the medium when the diaphragm breaks.
An ampoule with starting fuel for igniting the propellant components of liquid-propellant rocket engines (LRE) is known that comprises a body with an inlet and an outlet, two diaphragm units, the diaphragms of which are air-tight fastened along the periphery in the body from the inlet and outlet sides (the book "Liquid-Propellant Rocket Engine Design and Engineering," edited by G. G. Gakhun, Moscow, Mashinostroenie, 1989, p. 75, FIG. 4.5). In this known ampoule design diaphragm units with rupturable diaphragms are used.
In this technical solution, a diaphragm is broken under the effect of medium pressure, and bending the diaphragm (opening the flow section) is carried out due to the pressure drop thereon that is defined, in particular, by the flow rate of the liquid. If the liquid flow rate and, accordingly, the pressure drop on the diaphragm are low, then the diaphragm may first break only partially and then may bend to an arbitrary extent.
In view of the fact that after the diaphragm breaks, it or its parts occupy an indefinite and unstable position at different flow rates, such a design does not ensure stable hydraulic characteristics.
This is especially important when the ampoules are mounted in parallel main lines of a multi-chamber LRE, where it is necessary to ensure a strictly identical distribution of flow rates along those main lines after the break of diaphragms.